<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <title>Title</title>
    <style>
        /* *{
            background-color: red;
        } */
        /* div {
            background-color: blue;
        } */
        #div01 {
            background-color: blanchedalmond;
            border: 2px red solid;
        }
        .div0203{
            background-color: aqua;
            border: 2px yellow solid;
        }
    </style>
</head>
<body>
    <input type="submit" value="登录">

    <div id="div01">div01</div>
    <div class="div0203">div02</div>
    <div class="div0203">div03</div>
</body>
</html>